Vapor deposition apparatus with rotating drum mask

ABSTRACT

Apparatus and method for depositing a stripe of metal on a metallic strip, comprising a peripherally slitted wheel or drum enclosing a vaporizing boat into which the metal to be deposited is fed and heated to vaporization. A strip of metal of resistance material which is to be coated along its central portion is entrained and moved along the outer periphery of the slitted wheel or drum so that the edges of the slit define the limits of the coating to be deposited onto the metal strip. Both the slit wheel and vaporizing boat are water cooled. The entire assembly comprising the slit wheel, vaporizer and wire feeder are contained within an evacuated container. A heating current is passed through a length of the strip to heat it before it is coated. A modification is to provide a wheel with peripheral holes for depositing longitudinally spaced spots of metal, instead of a strip of metal, onto a metallic base strip. A plurality of such wheels may be used for simultaneously depositing metallic spots onto a plurality of metal strips disposed side-by-side.

llnite States Patent [191 Ridout i 1 VAPOR DEPOSITION APPARATUS WITHROTATING DRUM MASK {22] Filed: Dec. 21, 1973 [21] Appl. No.: 427,124

[52] 11.8. C1 118/49.1, 118/504, 118/620 [51} 1nt.Cl. C23c 13/12 [58]Field of Search 118/620, 48-495, 118/504, 505, 301, 406; 117/1071, 38

[56] References Cited UNITED STATES PATENTS 2,402,269 6/1946 Alexanderet a1, ll7/l07.l X 2,656,284 10/1953 Toulmin, Jr. 1l7/l07.l X 2,665,229l/1954 Schuler et al 118/49 X 2,948,261 8/1960 McGraw, Jr. 118/493,102,046 8/1963 Bushey 118/301 X 3,498,259 3/1920 Braguier 118/493,735,728 5/1973 Krumme et al, 118/49 3,738,315 6/1973 Sweitzer ll8/49.5

FOREIGN PATENTS OR APPLICATIONS 618,597 2/1949 Great Britain 118/301 141 Feb. 18, 1975 Primary Examiner Morris Kaplan Attorney, Agent, orFirm-William .l. Ruano ABSTRACT Apparatus and method for depositing astripe of metal on a metallic strip, comprising a peripherally slittedwheel or drum enclosing a vaporizing boat into which the metal to bedeposited is fed and heated to vaporization. Astrip of metal ofresistance material which is to be coated along its central portion isentrained and moved along the outer periphery of the slitted wheel ordrum so that the edges of the slit define the limits of the coating tobe deposited onto the metal strip. Both the slit wheel and vaporizingboat are water cooled. The entire assembly comprising the slit wheel,vaporizer and wire feeder are contained within an evacuated container Aheating current is passed through a length of the strip to heat itbefore it is coated.

9 Claims, 9 Drawing Figures l VAPOR DEPOSITION APPARAgUS WITH ROTATINGDRUM MA K This invention relates to apparatus for coating a strip ofmetal onto a base metallic strip, such as one of resistance material,or, in the alternative, for coating a se ries of metallic spots thereon.

In the past, the common way of applying a coated strip of metal onto abase strip has been by an electrolytic method by first masking the sidesof the strip and, after the electrolytic process, dissolving the maskingstrips and then finally washing out the resulting liquid. This involvesconsiderable apparatus, chemicals, large tanks of water and extendedtime for manufacture that have made the cost of the process exhorbitant.

An object of the present invention is to overcome the abovenameddisadvantages and high costs by eliminating the necessity of masking thestrip and using solutions for dissolving the masking material.

An object of the present invention is to overcome the abovenameddisadvantages and high costs by eliminating the necessity of masking thestrip and the masking material.

A more specific object of my invention is to provide a novel apparatusfor applying a strip or spots of vaporized metal to the strip afterelectrically heating a portion of the strip in a vacuum chamber.

Other objects and advantages will become more apparent from a study ofthe following description taken with the accompanying drawings wherein:

FIG. 1 is an elevational view, with the cover removed, of apparatus fordepositing vaporized metal in the form of a central strip portion onto ametallic base strip, in accordance with the present invention;

FIG. 2 is a side view thereof, reduced in size and showing the cover inplace, which cover is shown partly cutaway to expose the interior parts;

FIG. 3 is an enlarged, vertical, cross-sectional view of the slit wheeland vaporizer shown in FIGS. 1 and 2;

FIG. 4 is an enlarged, fragmentary view of a portion of the strip 9illustrated in FIGS. 1 and 2, showing the deposited central stripportion 36 thereon;

FIG. 5 is a vertical, plan view, partly in cross-section, showing amodification wherein radial holes are provided to apply a series oflongitudinally spaced spots, instead of a strip, on the base metallicstrip;

FIG. 6 is an elevational view, partly in vertical crosssection, asviewed from the left of FIGS. 5;

FIG. 7 is an enlarged, fragmentary view of a portion of the spottedstrip 61 illustrated in FIGS. 5 and 6;

FIG. 8 is a further modification showing multiple slit wheels forapplying central coated strips to a plurality of base metallic strips,simultaneously; and,

FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8.

Referring more particularly to FIGS. 1, 2 and 3, of the drawing, numeral1 generally denotes apparatus for vaporizing metal and depositing it inthe form of a strip along a central portion of a base metallic strip ofelectrical resistance material. The apparatus is mounted on a back plateor support 2 and is enclosed by a cover 3 which may be either round, toform a bell jar, or rectangular in shape and sealed to the back plate 2by a seal ing strip 6 of neoprene rubber or other suitable material toenable retention of a vacuum in the space enclosed by the cover 3. Thecover 3 is hingedly mounted on back plate 2 by a double hinge 4, 5 andmay be sealed tightly thereagainst by sea] 6 and by a handle and camlock (not shown), such as commonly used in the past on iceboxes and thelike. An evaporation boat 23 heats to vaporization a strip of aluminum24 or other metal to form the coating or stripe 36.

The space within cover 3 is evacuated by a mechanical pump driven by amotor, generally denoted by numeral 8, and a diffusion pump 7 of anywell known type with suitable controls for allowing roughing, that is,partial evacuation by the mechanical pump and further evacuation by thediffusion pump. The diffusion pump has an outlet leading through a hole7' in the back plate 2 to evacuate the space covered by sealed cover 3.A gate valve 46a is supported on the back plate for controlling the flowof air exhausted from the space in cover 3.

A strip 9 of metal, particularly metal having high electricalresistance, such as an alloy of iron, nickel and cobalt sold under thetrademarksvKOVAR and FER- NICO, is unwound from a feed spool 10, passedover a guide spool 11 and thence over a centrally slitted drum or wheelgenerally denoted by numeral 15. A stripe 36 (see FIG. 4) of aluminum orof other vaporized metal is deposited on strip 9 through a slit in thewheel, thereafter the strip is passed over a second guide spool 12 andfinally wound onto a take-up spool 13. The slit wheel assembly comprisesthree essential parts: an inner wheel 20 an outer wheel 21, and aspindle 16 on which both are rigidly mounted and spaced apart by slit 9.This assembly is water cooled.

The spindle 16 is essentially a piece of pipe threaded at one end andwith a flange 34 with recessed O ring attached. A small pipe 42 locatedconcentrically carries cooling water to the inner and outer slit wheels.The inner wheel 20 is permanently attached to the spindle.

Both slit wheels 20 and 21 have cavities through which cooling waterflows. It enters the spindle via a rotating seal 18 outside the vacuumchamber, and flows into a cavity in the inner slit wheel 20 through ahole 38 in the spindle. When the cavity is full the water flows outthrough a radially located inlet pipe 40 connected to the pipe 42concentric with the spindle. Inlet pipe 37 and outlet pipe 43 areprovided for water flow.

The outer wheel 21 is similar to the inner and has a water cavity, thechief difference being that it is drilled and tapped to fit onto thethreaded end of the spindle. By this means, the wheel is pulled uptightly against the O ring in the spindle flange, thus sealing in thecooling water. The outer slit wheel 21 differs in that it has anadditional water cavity 410 supplied by a radial pipe 41 thence flowinginto the pipe 42 concentric with the spindle. Water flows into the maincavity through holes 39 drilled in the threaded portion of the spindle.The water cavities of the inner and outer split wheels are thus inparallel. Before taking off the outer slit wheel 21, the water isremoved by so positioning the wheel that the radial pipe is verticallybelow the spindle and applying a few pounds of pressure of compressedair.

Provision is made for adjusting the width of the aluminum stripe byinserting washer of appropriate thickness between the outer slit wheel21 and the spindle flange 19. An additional 0 ring to that shown is letinto the outer slit wheel 21 to effect a water seal. The spindle issupported by ball races 17 (not self'aligning) and is insulatedelectrically from the back plate 2 in much the same way as the outerspindles. The spindle is held in position by a ring 18 on a threadedportion of the spindle outside the vacuum chamberrA window 45 isprovided to enable viewing of the interior of the space or chamberenclosed by lid 3. A graphite brush assembly is located on the spindlenext to the rotating water seal.

The feeder for the aluminum wire 24 consists of four separateassemblies: (1) knurled wheel assembly; (2) Wilson seal assembly); (3)Motor and gearbox; and (4) spool support and guide tube.

The knurled wheel assembly 30 for feeding aluminum wire into evaporatingboat 23 comprises two bars 30a, 3012, each carrying a knurled wheel 22aon a shaft inserted in small ball races pressed into opposite sides ofthe bars, which are clamped to a pivot 33 by means of two tie rodslocated at opposite ends of the bars. By adjusting the nuts on the tierods, suitable clearance between the knurled wheels may be obtained. Thepivot 33 is extended to serve as a support for the knurled wheelassembly and is terminated at the end by a flange bolted to the backplate 2.

The boat 23 is preferably made of boron nitride or other conductingmaterial. The aluminum strip is electrically heated in the boat by powerlead-ins comprising copper bars 28 extending through and insulated toback plate 2 and connected to the boat through copper delivery tubes 26,27 which are constricted at the'point of entry 35 through the slitbetween wheels and 21. The bars 28 are cooled by passing cooling waterin pipes 26, 27 therethrough.

A length of strip 34 between idler wheel 11 and drum 15 may beelectrically preheated by a source of voltage V connected to theirshafts through brushes B. Such preheating improves adherence of stripe36.

FIGS. 5, 6 and 7 show a modification for applying spaced spots ofvaporized metal, instead of a strip of metal, onto the base metallicstrip 61. Numeral 1 denotes a back plate on which is mounted apparatusgenerally denoted by numeral 50 for depositing spots of vaporized metalonto strip 61, such as an electrical heater strip, for example, one ofan iron, nickel cobalt alloy, such as KOVAR. The wheel or drum 51 isrotatably mounted on a tubular shaft or pipe 52 by means of a pipeflange 53 bolted to the drum 51. A plurality of sprockets 54 projectradially outwardly from the peripheral surface of the drum for guidingthe strip 61, that is, by projecting sprockets 54 through holes 54extending along the edges of the strip. A plurality of circumferentiallyspaced holes 55 are provided through which vaporized metal is passed anddeposited on strip 61 in the form of spots, such as 60, shown in FIG. 7.

A water cooling pipe 57 is provided with an inlet pipe 58 to allow theflow of cooling water through boat 56 which contains the vaporizingmetal, such as gold, which is fed into vaporizing boat 56 in the form ofa strip through tube 58. A masking strip 59, entrained about idlerwheels 64 and 65, will mask the sides of the strip (or any otherportion).

FIG. 7 shows the resultant design. The strip 61 is entrained about guidespools 62 and 63 and underneath arcuate guide 66 so as to be laid ontomasking tape 59 before vaporized metal is deposited thereon. Theironnickel stamped lead frame strip 61 may have cut-out portions such as61a which provide inwardly projecting fingers 61b whose innerextremities would be coated with gold spots, four in number,corresponding to the peripheral portions of a single spot 60.

FIGS. 8 and 9 show a modification of the invention illustrated in FIGS.1 to 4 inclusive for depositing a stripe of metal 36 onto a metallicstrip 9, preferably of resistance material. As shown in FIGS. 8 and 9, aplurality of wheels 70 may be provided with V-shaped slots and arrangedside-by-side and guided by locating wheels 74 and a spring loadedlocating wheel 73. A supply spool feeds aluminum wire 77 into aevaporating boat 76 serving all of the slit wheels. A water cooledshield is provided between each slit wheel. Radiation shields 78 areprovided on the outside of the slit wheels at the ends of the gangassembly. Thus a plurality of metal strips 9, when entrained about theslits between the respective wheels, will be coated simultaneously withstripes 36 centrally and longitudinally of the strip, as shown in FIG.4.

Such deposited stripes may be used for numerous purposes, including themaking of a bimetallic strip, such as, by depositing a silver-coppereutectic stripe on a strip 9 of 0.01 inch iron-nickel cobalt alloy. Thiscomprises a significant improvement over the common method of bonding byrolling a silver-copper eutectic foil about 2 mils thick onto anickel-iron strip. Foil is difficult to roll, particularly thinner than1 mil.

It will be readily apparent to those skilled in the art that variationsmay be made in the illustrative embodiments heretofore described. Forexample, instead of putting the vaporization boat inside the slit wheel,it may be put on the outside and under it while passing the metallicstrip 9 inside the wheel adjacent the periphery. A plurality of suchunits may be provided sideby-side, as illustrated in FIGS. 8 and 9.

I claim:

1. Apparatus for depositing vaporized metal along the intermediatelongitudinal portion of an elongated base strip, comprising a drumhaving central opening means extending along the entire periphery, meansfor rotating said drum about its axis, a source of metallic vapor on oneside of said opening means, means for longitudinally moving a base stripentrained on the other side of the drum overlying said openingimmediately adjacent said opening means, said source of metallic vaporbeing contained within said drum and comprising a boat-like containerwhich is heated to vaporization temperature of a strip of metalprogressively fed into said container, and said base strip beinglongitudinally driven along a portion of the outer periphery of saiddrum so that the inner surface exposed to said slit will become coatedwith said vaporized metal, the edges of the slit defining the boundariesof the coated strip, said base strip being driven by a motor and furtherentrained about a plurality of idler wheels, a source of potential beingapplied between a brush which contacts the shaft of one of said idlerwheels and a brush which contacts the shaft of said drum so as toprovide electric heating current-to a portion of said base stripextending between the periphery of one of said idler wheels and of saiddrum, to effect preheating of said portion before deposition ofvaporized metal thereon through said slit, and means contacting saiddrum beyond the area of strip contact whereby to remove excess depositedmetal from the edges of said slit.

2. Apparatus as recited in claim 1, together with a back plate rotatablymounting said drum, and together with a pivotally mounted cover having aflexible sealing gasket about the mouth of said cover for engaging andforming a seal with said back plate, and evacuating means for evacuatingthe space enclosed by said cover.

3. Apparatus as recited in claim 1 together with water cooling conduitsextending through a spindle on which said drum is rigidly connected andthrough interior portions of said drum and back plate on which saidspindle is rotatably mounted.

4. Apparatus as recited in claim 3 together with a pair of electrical,water-cooled terminals extending through said back plate and to-the endsof said container for passing electric heating current through saidcontainer.

5. Apparatus as recited in claim 1 together with a supply roll of stripmaterial and means for longitudinally moving said strip material intosaid container to effect vaporization thereof.

6. Apparatus as recited in claim 1 wherein said opening means is in theform of a plurality of holes extending along the entire periphery ofsaid drum so as to de- 6 posit spots of vaporized metal onto said basestrip.

7. Apparatus as recited in claim 6 wherein a masking strip islongitudinally moved between the periphery of said drum and the basestrip onto which said vaporized metal is to be deposited.

8. Apparatus as recited in claim 1 comprising a plurality of drums inside-by-side relationship with said drum, each having a circumferentialslit and a plurality of base strips simultaneously moved longitudinallyoutside said slits, whereby the base strips which are moved along saidslits are simultaneously coated with vaporized metal.

9. Apparatus as recited in claim 1 wherein said means to remove excessdeposited metal comprises knife means projecting into the sides of saidslit.

1. Apparatus for depositing vaporized metal along the intermediatelongitudinal portion of an elongated base strip, comprising a drumhaving central opening means extending along the entire periphery, meansfor rotating said drum about its axis, a source of metallic vapor on oneside of said opening means, means for longitudinally moving a base stripentrained on the other side of the drum overlying said openingimmediately adjacent said opening means, said source of metallic vaporbeing contained within said drum and comprising a boat-like containerwhich is heated to vaporization temperature of a strip of metalprogressively fed into said container, and said base strip beinglongitudinally driven along a portion of the outer periphery of saiddrum so that the inner surface exposed to said slit will become coatedwith said vaporized metal, the edges of the slit defining the boundariesof the coated strip, said base strip being driven by a motor and furtherentrained about a plurality of idler wheels, a source of potential beingapplied between a brush which contacts the shaft of one of said idlerwheels and a brush which contacts the shaft of said drum so as toprovide electric heating current to a portion of said base stripextending between the periphery of one of said idler wheels and of saiddrum, to effect preheating of said portion before deposition ofvaporized metal thereon through said slit, and means contacting saiddrum beyond the area of strip contact whereby to remove excess depositedmetal from the edges of said slit.
 2. Apparatus as recited in claim 1,together with a back plate rotatably mounting said drum, and togetherwith a pivotally mounted cover having a flexible sealing gasket aboutthe mouth of said cover for engaging and forming a seal with said backplate, and evacuating means for evacuating the space enclosed by saidcover.
 3. Apparatus as recited in claim 1 together with water coolingconduits extending through a spindle on which said drum is rigidlyconnected and through inteRior portions of said drum and back plate onwhich said spindle is rotatably mounted.
 4. Apparatus as recited inclaim 3 together with a pair of electrical, water-cooled terminalsextending through said back plate and to the ends of said container forpassing electric heating current through said container.
 5. Apparatus asrecited in claim 1 together with a supply roll of strip material andmeans for longitudinally moving said strip material into said containerto effect vaporization thereof.
 6. Apparatus as recited in claim 1wherein said opening means is in the form of a plurality of holesextending along the entire periphery of said drum so as to deposit spotsof vaporized metal onto said base strip.
 7. Apparatus as recited inclaim 6 wherein a masking strip is longitudinally moved between theperiphery of said drum and the base strip onto which said vaporizedmetal is to be deposited.
 8. Apparatus as recited in claim 1 comprisinga plurality of drums in side-by-side relationship with said drum, eachhaving a circumferential slit and a plurality of base stripssimultaneously moved longitudinally outside said slits, whereby the basestrips which are moved along said slits are simultaneously coated withvaporized metal.
 9. Apparatus as recited in claim 1 wherein said meansto remove excess deposited metal comprises knife means projecting intothe sides of said slit.